1,245 research outputs found
Changes in select phenolic compounds during ethanol fermentation and acetification of raspberry, blueberry and persimmon
Polyphenols are major dietary components in fruits and vegetables. Many research and epidemiological studies have reported that phenolic compounds, such as anthocyanins, may have a protective effect against various degenerative diseases. Phenolics in grape wine have been extensively studied but information on changes of phenolics in wine and vinegar made from other fruit crops is limited, however. This research started with the objective of determining the effect of proteases in preventing phenolic and, specifically, anthocyanin degradation in the ethanolic fermentation of black raspberries to reduce sugar content. The results of this study led to investigations of changes of other polyphenols in persimmons and blueberries during both ethanolic (vinification) and vinegar (acetification) fermentations. Initial results showed that a 1% neutral bacterial protease could retain anthocyanin in open vinification of black raspberries but the protease treatment provided no benefit when a closed fermentation was used. Additional research using closed vinification followed by acetification of persimmons indicated that phenolics were significantly affected by these fermentations. Phenolics in astringent persimmons were significantly degraded during both vinification and acetification while phenolics in non-astringent persimmons actually increased during vinification but decreased during acetification. In blueberries, anthocyanin and epicatechin were increased during vinification but decreased during acetification. The lipid-protective properties of fruit wine and vinegar was also investigated. In this study of antioxidant properties, blueberry vinegar was more effective than blueberry juice or blueberry wine in preventing EPA and DHA degradation in salmon oil-in-water emulsion model system. This thesis research provides informative insights concerning changes in polyphenols, such as anthocyanin, during vinification and acetification of some fruit crops. The information is especially beneficial to the juice, wine and vinegar industries since polyphenols are one of the major health promoting constituents in fruit juices, wines and vinegars
Physico-chemical and electrical properties of bismuth chromate solid solutions
Bismuth chromium solid solutions, with a general formula Bi6-xCr2Oδ, where -1 ≤ x ≤ 2, were successfully synthesized via the conventional solid state method. The phases of the synthesized samples were determined by X-ray diffraction (XRD) analysis. The properties of single-phase compounds were characterized by using differential thermal analysis (DTA), thermal gravimetric analysis (TGA), AC impedance spectroscopy, and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The occurrence of phase transitions was confirmed by DTA and TGA, where a thermal event was observed by DTA at around 800°C. In addition, TGA studies also showed that there was a weight loss at around 800°C. Elemental analysis of Bi6Cr2O15and its solid solutions by ICP-AES showed a good agreement between the expected value and the experimental value on the compositions, with no evidence of any systematic deviation from stoichiometric. Electrical properties of Bi6Cr2O15and its solid solutions were investigated by using AC impedance spectroscopy from 300°C to 650°C. Ionic conductivity increased with the increasing temperature and bismuth content, and the best ionic conductivity was observed for Bi7Cr2O16.5. The activation energy (Ea) of Bi6Cr2O15and its solid solutions were in the range of 1.22-1.32 eV
Preparation and characterization of bismuth-niobium oxide ion conductors
Oxide ion conductors have been attracting considerable attention for many years due to their application in technological devices such as solid oxide fuel cells, oxygen sensors and many more. In this study, material with desirable electrical properties in the Bi2O3- Nb2O5 binary system was studied. Bismuth-niobium oxide has been prepared by solid state reaction. Powder X-ray diffraction (XRD) analysis showed that single-phase materials were formed with a general formula of BixNbOδ: 2.5 ≤ x ≤ 6. Electrical properties of the single-phase materials in these solid solution series were studied by a.c. impedance spectroscopy. Conductivity measurements were also carried out in dry oxygen free nitrogen (OFN) in order to confirm the conduction species of the materials. Results showed that these materials appeared to be oxide ion conductors. Further characterizations of the materials using thermal analysis (DTA), thermogravimetric analysis (TGA) and the results showed that there were no thermal changes and phase transitions were observed and all the materials were thermally stable. Scanning electron microscopy (SEM) has been carried out to study the morphology of the materials and all the grain size of the samples were in micrometers
Mechanochemical synthesis and characterisation of bismuth-niobium oxide ion conductors
Bismuth niobate solid solutions, BixNbOδ(2.5≤x≤6), have been prepared using a mechanochemical method. The solid solutions were also prepared using a solid-state conventional method for comparison purposes. Bi3NbO7 was successfully obtained via a mechanochemical method at a lower synthesis temperature (milled at 1000 rpm for one hour followed by heating at 700oC for 24 h) than the conventional solid-state method. Electrical properties of the single-phase materials were studied by AC impedance
spectroscopy. Further characterization of the materials was carried out using differential thermal analysis (DTA) and thermogravimetric analysis (TGA). The results showed that
no thermal changes and phase transitions were observed and all materials were thermally stable
Delay QoS and MAC Aware Energy-Efficient Data-Aggregation Routing in Wireless Sensor Networks
By eliminating redundant data flows, data aggregation capabilities in wireless sensor networks could transmit less data to reduce the total energy consumption. However, additional data collisions incur extra data retransmissions. These data retransmissions not only increase the system energy consumption, but also increase link transmission delays. The decision of when and where to aggregate data depends on the trade-off between data aggregation and data retransmission. The challenges of this problem need to address the routing (layer 3) and the MAC layer retransmissions (layer 2) at the same time to identify energy-efficient data-aggregation routing assignments, and in the meantime to meet the delay QoS. In this paper, for the first time, we study this cross-layer design problem by using optimization-based heuristics. We first model this problem as a non-convex mathematical programming problem where the objective is to minimize the total energy consumption subject to the data aggregation tree and the delay QoS constraints. The objective function includes the energy in the transmission mode (data transmissions and data retransmissions) and the energy in the idle mode (to wait for data from downstream nodes in the data aggregation tree). The proposed solution approach is based on Lagrangean relaxation in conjunction with a number of optimization-based heuristics. From the computational experiments, it is shown that the proposed algorithm outperforms existing heuristics that do not take MAC layer retransmissions and the energy consumption in the idle mode into account
Pb(II) removal from wastewater by modified activated carbon in batch and fixed-bed column studies: synthetic and real wastewater application
Activated carbon (AC) prepared from palm kernel was modified by citric acid (CA) to enhance its ability for Pb(II) removal from aqueous solutions. The product obtained was characterized using energy dispersive X-ray spectroscopy, Brunauer-Emmett-Teller method, Fourier transform infrared, spectroscopy, and field emission scanning electron microscope (FESEM). The adsorption of Pb(II) ions onto CA modified activated carbon (AC-CA), was studied in both batch and column mode operations. In the batch studies, a wide range of operating parameters, such as adsorbent dose (0.1–0.95 g), initial metal ion concentration (50–150 mg/L), contact time (15–150 min), and pH (1–5), were investigated. Equilibrium data were fitted using Langmuir, Freundlich, first and second order kinetic models. The experimental data were best characterized by pseudo-second order kinetic model and Langmuir isotherm models; indicative of chemisorption and monolayer adsorption, respectively. ACs and AC-CA were mainly microporous with pores in the range of 1.2–1.76 nm. Although the surface area of AC-600 (1,559.9 m ² /g) was much higher than that of AC-CA (1,267.1 m ² /g), the Pb(II) sorption capacity of AC-CA was larger than that of AC-600. The AC and AC-CA, both showed high Q max of 81.0 and 103.1 mg/g, the high adsorption capacity of the adsorbents is promising in the development of low cost and novel adsorbent. It is concluded that Pb(II) ions removal using palm kernel shells based adsorbent modified with citric acid would be an efficient technique for economic treatment of wastewater
A comparative study of Yttrium doped ceria ceramics synthesized using mechanochemical and solid state methods
In this work, 10 mol% yttrium-doped ceria powders, Ce0.9Y0.1O1.95, were synthesised using a new mechanical technique, mechanochemical reaction, in which both impact action and shearing forces were applied for efficient fine grinding, subsequently leading to higher homogeneity of the resultant powders. Ce0.9Y0.1O1.95 prepared using this new technique was systematically compared with a sample of the same prepared using conventional solid-state methodology. X-ray diffraction analysis showed all prepared samples were single phase with a cubic fluorite structure. Generally, Y2O3-doped CeO2 electrolytes prepared by mechanochemical reactions were stable at a lower temperature (1100 °C) compared with a sample of the same synthesised using the conventional solid-state method. Characterisations using differential thermal analysis (DTA) and thermogravimetric analysis (TGA) showed no thermal changes and phase transitions, indicating all materials were thermally stable. The electrical properties of the samples investigated by AC impedance spectroscopy in the temperature range 200–800 ˚C are presented and discussed. Scanning electron microscopy (SEM) was used to study the morphology of the materials. Fine-grained powders with uniform grain-size distribution were obtained from the mechanochemical reaction
Acute morphine induces matrix metalloproteinase-9 up-regulation in primary sensory neurons to mask opioid-induced analgesia in mice
<p>Abstract</p> <p>Background</p> <p>Despite decades of intense research efforts, actions of acute opioids are not fully understood. Increasing evidence suggests that in addition to well-documented antinociceptive effects opioids also produce paradoxical hyperalgesic and excitatory effects on neurons. However, most studies focus on the pronociceptive actions of chronic opioid exposure. Matrix metalloproteinase 9 (MMP-9) plays an important role in neuroinflammation and neuropathic pain development. We examined MMP-9 expression and localization in dorsal root ganglia (DRGs) after acute morphine treatment and, furthermore, the role of MMP-9 in modulating acute morphine-induced analgesia and hyperalgesia in mice.</p> <p>Results</p> <p>Subcutaneous morphine induced a marked up-regulation of MMP-9 protein in DRGs but not spinal cords. Morphine also increased MMP-9 activity and mRNA expression in DRGs. MMP-9 up-regulation peaked at 2 h but returned to the baseline after 24 h. In DRG tissue sections, MMP-9 is expressed in small and medium-sized neurons that co-express mu opioid receptors (MOR). In DRG cultures, MOR agonists morphine, DAMGO, and remifentanil each increased MMP-9 expression in neurons, whereas the opioid receptor antagonist naloxone and the MOR-selective antagonist <smcaps>D</smcaps>-Phe-Cys-Tyr-<smcaps>D</smcaps>-Trp-Arg-Thr-Pen-Thr-NH<sub>2 </sub>(CTAP) suppressed morphine-induced MMP-9 expression. Notably, subcutaneous morphine-induced analgesia was enhanced and prolonged in <it>Mmp9 </it>knockout mice and also potentiated in wild-type mice receiving intrathecal injection of MMP-9 inhibitors. Consistently, intrathecal injection of specific siRNA targeting MMP-9 reduced MMP-9 expression in DRGs and enhanced and prolonged morphine analgesia. Subcutaneous morphine also produced heat hyperalgesia at 24 h, but this opioid-induced hyperalgesia was not enhanced after MMP-9 deletion or inhibition.</p> <p>Conclusions</p> <p>Transient MMP-9 up-regulation in DRG neurons can mask opioid analgesia, without modulating opioid-induced hyperalgesia. Distinct molecular mechanisms (MMP-9 dependent and independent) control acute opioid-induced pronociceptive actions (anti-analgesia in the first several hours and hyperalgesia after 24 h). Targeting MMP-9 may improve acute opioid analgesia.</p
How E-Servqual Affects Customer\u27s Online Purchase Intention?
With the boom of Internet, Internet has become one of the consumers’ online shopping channels. However, there is different in online shopping situation is because of consumers in different cultures and countries have different online shopping behavior is worth to discuss. This study is to explore the Internet users’ online shopping situation in developing country, Malaysia, and 118 questionnaire respondents were collected. Statistical analysis software SPSS 17.0 and AMOS 6.0 were used to analyze the impact on e-service quality, satisfaction, trust, and purchase intention. The model fit of this study was in an acceptable level, and this indicates that the theoretical model of this study supports the description of e-service quality for e-retailers that online shopping situation will be effected by trust and satisfaction. The result of this study will be available for those who interested in developing a transnational e-retailer as a reference, as well as academic research on cross-cultural comparative analysis
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